Caged Gold Nanostars for Tunable Plasmonic Resonance
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Solution Overview
Problem
There is a need for plasmonic-active nanoparticles that combine the tunable optical properties of nanostar-based particles with the loadable properties of nanoparticles like nano rattles, suitable for in vivo use without the need for surfactants.
Innovation Solution
The development of caged gold nanostars (C-GNS) is achieved by dispersing bimetallic nanostars into a polyvinylpyrrolidone solution and performing either a galvanic replacement reaction or a galvanic replacement-free reaction to form gold-coated or silver-coated C-GNS, which have a hollow gold or silver shell, allowing for loading with compounds and tunable plasmon resonance from the visible to the near-infrared spectral range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If nanostar-based particles are used to achieve tunable optical properties, then optical performance is improved, but loadable functionality is lost
Solution Approach 1:
The patent embeds a hollow core structure within the nanostar morphology, creating a nested architecture where the core provides loading capacity and the nanostar shell provides optical performance. This allows simultaneous achievement of both tunable optical properties and loadable functionality.
Solution Approach 2:
The patent creates composite nanoparticles combining the nanostar shell material with a hollow core, integrating the advantageous properties of both components - the optical enhancement from the nanostar structure and the loading capacity from the hollow core.
2Adaptability or versatility
If nano rattles are used to achieve loadable properties, then loading capacity is improved, but tunable optical properties are lost
Solution Approach 1:
The patent places a hollow core (providing loading capacity like nano rattles) inside a nanostar shell (providing tunable optical properties), creating a nested structure that combines the beneficial features of both particle types.
Solution Approach 2:
The patent assigns different functional qualities to different parts of the nanoparticle - the hollow core provides loading capacity while the nanostar shell provides optical properties, allowing each region to optimize its local function.
3Stability of the object's composition
If surfactants are used in nanoparticle synthesis, then particle stability is improved, but in vivo suitability deteriorates
Solution Approach 1:
The patent removes surfactants from the nanoparticle structure entirely, achieving stable particles through intrinsic structural design (hollow core with nanostar shell) rather than extrinsic stabilizing agents, thereby improving in vivo suitability.
Solution Approach 2:
The nanoparticle structure itself provides stability through its hollow core-nanostar shell architecture, eliminating the need for external surfactant stabilization and enabling direct in vivo application.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The C-GNS particles exhibit enhanced local electric field enhancement, thermal stability, and increased NIR absorption, making them suitable for photothermal therapy and in vivo imaging, while maintaining the tunable optical properties and loadable functionality of nanostar-based particles without the use of surfactants.
Implementation Method 1
exchanging gold ions with silver atoms of the bimetallic nanostar in a galvanic replacement reaction
Implementation Method 2
redispersing the one or more gold-coated bimetallic nanostars into a second solution of hydrogen peroxide to etch the gold layer and remove the silver
Implementation Method 3
plasmonic-active caged gold nanostars having a hollow gold shell surrounding the essentially spherical core... tunable plasmon resonance from the visible to the near-infrared (NIR) spectral range
Data Source
AI summary
Methods are provided for making caged gold nanostars (C-GNSs). In one method, a layer of gold is deposited on the silver layer of bimetallic nanostar (BNS) particles in a galvanic replacement-free reaction and the silver is subsequently removed via hydrogen peroxide etching. In another method, gold ions are exchanged with the silver atoms of the BNS particles in a galvanic replacement reaction. Both methods result in a hollow gold shell around a gold nanostar core that enables loading with dyes for in vitro and in vivo detection of the C-GNSs and provides an internal standard in sensing. The C-GNS particles have a greater local electric field enhancement from the visible to the NIR spectral range relative to plasmonic-active GNSs of similar diameter that lack the hollow gold shell. Dye-loaded C-GNS particles are demonstrated for in vivo hyperspectral imaging and as photothermal transducers in the treatment of solid tumors.